1. Field
The following description relates to a rechargeable lithium battery.
2. Description of the Related Art
In recent times, due to reductions in the size and weight of portable electronic equipment in accordance with developments of the electronic industries, use of such portable electronic equipment has become increasingly popular. A battery having a high energy density is needed for use as a power source in such portable electronic equipment. Rechargeable lithium batteries have a high energy density, thus research into rechargeable lithium batteries has been actively conducted.
Lithium-transition element oxides that are capable of intercalating and deintercalating lithium ions have been used as a positive active material of a rechargeable lithium battery. Various crystalline or amorphous carbon-based materials or carbon composites have been used as a negative active material. To fabricate positive or negative electrodes, either the positive or negative active materials are coated on a current collector at an appropriate thickness and length, or the positive or negative active materials are made in the form of a film.
The positive and negative electrodes are then wound or stacked while interposing an insulating separator therebetween to fabricate an electrode assembly. The electrode assembly is enclosed in a can or another case, and an electrolyte solution is injected to fabricate a prismatic rechargeable battery. Compared to using a can as a battery container, using a pouch as a battery container is advantageous in that the shape may be flexibly changed and the size of the container may be increased.
However, the pouch-type battery container is disadvantageous in that it may be easily deformed and damaged by an external physical impact and it may become swollen when exposed to a high temperature. Such disadvantages are more serious in a rechargeable lithium battery using a liquid electrolyte solution than in a rechargeable lithium battery using a polymer electrolyte.
Therefore, a polymer electrolyte rechargeable lithium battery is typically used in a battery having a pouch-type battery container. The polymer electrolyte rechargeable lithium battery has the advantages that it does not leak, it is safe, it is stable at high temperatures and it may resist an external physical impact to some extent. However, when the physical strength of the battery is increased in order to increase the resistance against an external physical impact, the performance of the battery may be compromised due to an increase in the internal resistance of the battery.